It really depends on your metabolism, your COMMITMENT, exercise levels, what you are willing to do.
I lost my first 45 pounds in 4 months- NO cheats during that time, and lots of intense exercise, both cardio and weights, daily. No cheat days, no cheat meals, no "I deserve a break. It was pretty intense, but worth it to me.
Most others find a two pound a week, dropping to one pound later, more sustainable because you don't have to make such a drastic lifestyle change.
It all depends on you and your body chemistry
Mel